Part two

"Listen to me, my friend. (It would be most unusual to call someone "countryman" in this way. ) The Pilman radiant is quite an easy thing. Imagine, you spin a globe and fire a gun at it. ("fire a gun" might be more natural than "shoot a revolver" here)  (*** this looks like an old translator's note left in in error ! "it’s better to use something more colloquial") The holes are going to lie down in a smooth curve. The point is that you call the first serious discovery of mine the elementary fact: all the six zones of the Visit are aligned on our planet surface as if someone had** a gun located somewhere on the Earth-Deneb line, and had fired it at the Earth six times.

[all the six zones of the Visit are aligned on our planet surface (you don't really want "the way" here) as if someone had** fired a gun, which is located somewhere on the Earth-Deneb line, at the Earth six times.]

Deneb is the alfa (you might want to use "alpha")  of the Cygnus constellation, and the spot from which someone fired,  as it were, (this is probably better than "so to say" here) is called the Pilman radiant.

* Really this is a new idea and should be in a new sentence. Joining two sentences with a comma is called a "comma splice", and so far as possible is to be avoided, though you could argue here that you are accurately recording the ungrammatical speech of the doctor. https://en.oxforddictionaries.com/grammar/the-comma-splice

This is pretty good. There are very few real errors: much of what I have suggested is to make the writing seem more natural in English. But it may be that the author, and you as translator, wanted to emphasise particular unusual speech patterns in the Russian, and carry those through to the English. If so, my apologies for trampling on them. I hope this was at least a little helpful.

** alternate:  "all the six zones of the Visit are aligned on our planet surface as if someone had** a gun located somewhere on the Earth-Deneb line, and had fired it at the Earth six times."

I don't know this novel, nor do I know any Russian, so my suggestions cannot be based on a better interpretation of the Russian. I will try to correct English errors, and where necessary suggest what I think is better English for what I think is your meaning. There is a text translation of it in English at  http://soviethistory.msu.edu/wp-content/uploads/2015/10/picnic.pdf

My attempt to translate the beginning of the novel called ' Roadside Picnic' by the Strugatsky brothers.(It's normal in English to capitalise novel titles like this.)

You have to create good out of evil, because there is nothing else you can create it out of.
Excerpts from the interview with Doctor Valentin Pilma  (capital for his title as a part of his name) on physics by the journalist Harmontski, recorded for radio in 19... , on the occasion of the second time he was awarded the Nobel Prize: (Your choices are not really wrong. The word order in English, though, would probably more naturally flow this way - interview - subject - interviewer - date - occasion. But this is not a requirement. Word order is flexible in English. The first requirement or objective is to choose a word order that is clear and easy to understand. Then the order may be adjusted to emphasise particular aspects.)

"Should we consider the so-called Pilman radiant to be your first serious discovery?" (In English the convention is to use inverted commas, like " ", to show direct speech as spoken. You can offset with dashes as you have, but it is not standard practice. )
"I guess you should not. The Pilman radiant is not the first, not serious and, strictly speaking, not a discovery. And it isn’t completely mine."
"You are probably joking, doctor. The Pilman radiant is a definition which is familiar to every schoolchild. "
"This notion doesn’t astonish me. ( "That doesn't surprise me" would be a more everyday way of expressing this.) The Pilman radiant was first discovered by a schoolchild. It's a pity, but I don’t remember his name. Look it up in Svetson’s ‘History of the Visitation’. * Everything is thoroughly described there. The radiant was discovered by the schoolchild first. The coordinates were published by a student, and the radiant was named after me for some reason.
"Yes, sometimes marvelous things happen to discoveries. Could you explain to our listeners, Doctor Pilman…"